Many commercial establishments provide shopping carts for the convenience of their customers in transporting merchandise through the stores and to the customer's vehicles. Some of these establishments experience substantial financial burdens through the loss of carts, be it through outright theft or simple removal from the premises and negligent abandonment.
Others have sought to solve the lost cart problem by providing means for automatically disabling, or immobilizing, the cart if it is being moved outside a prescribed use area.
One of the earliest such proposals is disclosed in U.S. Pat. No. 2,964,140, granted Dec. 13, 1960, to M. N. Brezny for "Anti-Theft Device for Carts". Brezny proposed that one or more of the cart casters be equipped with a mechanism for inserting a pin into an opening in the wheel in the caster to lock the wheel against turning. Brezny provided a mechanism for actuating the locking pin into locking position in response to the caster being moved over a magnetic strip at the perimeter of the prescribed use area.
There are several shortcomings to the Brezny anti-theft device. First, the device requires that the magnetic strip be installed about the entire perimeter of the prescribed use area or that the area be fenced and the magnetic strips laid in a limited exit, neither of which approaches may be practical. Secondly, the immobilizing mechanism of the Brezny system is exposed to the view of the cart user and, therefore, susceptible to being disabled and rendered ineffective by a person bent on removing the cart. Lastly, the Brezny system requires store personnel to carry a magnet for resetting the locking mechanism if the cart is retrieved.
Another approach to cart immobilization is disclosed in U.S. Pat. No. 4,242,668, granted Dec. 30, 1980, to W. Herzog for "Cart Theft Prevention System". Herzog's cart is immobilized by unlatching a support structure for the front wheels of the cart, allowing the front of the cart frame to fall down into contact with the ground. Unlatching of the front wheel structure is accomplished in response to a signal receiver detecting a signal from a transmitter at the exit of the prescribed use area or the receiver loosing receipt of a signal which covers only the prescribed use area. The principal disadvantage of the Herzog system lies in the rather extensive and complex modification required for the cart undercarriage, making the retrofitting of existing carts prohibitively expensive. And, again, like Brezny, Herzog leaves the immobilizing mechanism open to vandalism and destruction by a would-be thief.
A somewhat more practical theft deterrent system, one which can be readily adapted to existing carts, is disclosed in U.S. Pat. No. 4,772,880, granted Sep. 20, 1988, to L. W. Goldstein, et al. for "Shopping Cart Anti-Theft System". The system disclosed in this patent utilizes a clamp-on assembly which houses a battery-powered receiver for sensing when the cart leaves the area adjacent the business and includes means for disabling a wheel of the cart when the cart is outside the area. Because the assembly is exposed, it is relatively easily removed or disabled.
There continues to be a need for a cart theft prevention system which is reliable in operation and which cannot be easily overridden or disabled by the cart user.